The present invention relates to a steam turbine power plant.
A conventional nuclear power plant has a power generating system including a high-pressure steam turbine driven by steam generated by a nuclear reactor, a reheater for heating exhaust steam discharged from the high-pressure turbine to reduce moisture content, and a low-pressure turbine driven by the reheated exhaust steam. Steam generated by a nuclear reactor is saturated steam owing to the characteristic of the nuclear reactor and hence the exhaust steam discharged from the high-pressure turbine has a wetness fraction on the order of 10%. Reduction of the wetness fraction of the exhaust steam is effective in retarding the corrosion of the internal components of the turbine and the improvement of power generating efficiency.
A nuclear power generation system disclosed in Japanese Patent Laid-open No. 62-218606 has a high-pressure turbine and an intermediate-pressure turbine, which correspond to a high-pressure turbine included in a conventional nuclear power generating system, and a moisture separator placed in a steam line interconnecting the high-pressure turbine and the intermediate-pressure turbine to separate moisture from wet steam in cooperation with a moisture separator and a heater disposed above a low-pressure turbine.
In the nuclear power generating system disclosed in Japanese Patent Laid-open No. 62-218606, the moisture separators (reheaters) are placed in the steam line interconnecting the high-pressure turbine and the intermediate-pressure turbine, and in a steam line interconnecting the intermediate-pressure turbine and the low-pressure turbine to separate moisture from and to heat exhaust steam discharged from the high-pressure turbine and the intermediate-pressure turbine. The moisture separators, which are additional apparatuses, increase area necessary for installing the components of the nuclear power generating system.
The present invention has been made in view of the foregoing problem and it is therefore an object of the present invention to provide a steam turbine power plant provided with steam separators and capable of reducing area necessary for installing the steam separators.
According to a first aspect of the present invention, a steam turbine power plant includes: a high-pressure turbine to be driven by steam generated by a steam generator; a first reheater for separating moisture from steam discharged from the high-pressure turbine and heating the steam; an intermediate-pressure turbine to be driven by the steam heated by the first reheater; a second reheater for heating steam discharged from the intermediate-pressure turbine; and a low-pressure turbine to be driven by the steam heated by the second reheater; wherein the intermediate-pressure turbine discharges dry steam.
According to a second aspect of the present invention, a method of operating a steam turbine power plant including a high-pressure turbine to be driven by steam generated by a steam generator, a first reheater for separating moisture from steam discharged from the high-pressure turbine and heating the steam, an intermediate-pressure turbine to be driven by the steam heated by the first reheater, a second reheater for heating steam discharged from the intermediate-pressure turbine, and a low-pressure turbine to be driven by the steam heated by the second reheater comprises: separating moisture from and heating steam discharged from the high-pressure turbine; supplying the steam heated and dried by the first reheater to the intermediate-pressure turbine; making the steam supplied to the intermediate-pressure turbine expand such that the intermediate-pressure turbine discharges dry steam; heating steam discharged from the intermediate-pressure turbine by the second reheater; and supplying the heated steam heated by the second reheater to the low-pressure turbine.